Driving device of continuum robot

Abstract

The invention provides a driving device of a continuum robot. The driving device comprises a base; the rope hole plates are arranged at intervals; the variable-stiffness mechanism is supported on the base and located between the two adjacent rope hole plates, M variable-stiffness cams sharing a first rotating shaft are arranged in the variable-stiffness mechanism, and each variable-stiffness cam changes the tensioning degree of the corresponding driving rope passing through the fixed pulley through the radius change of the variable-stiffness cam; each cam mechanism assembly is arranged between every two adjacent rope hole plates, M elastic driving cams sharing a second rotating shaft are arranged in each cam mechanism assembly, a driven part is arranged on the upper portion of each driving cam, each driving rope penetrates through the top end of the corresponding driven part, and when the driving cams rotate, each driving rope is driven by the corresponding driven part to rotate. The bottom end of the driven part makes rolling contact with the top end of the driving cam, the driven part is driven to move in the radial direction of the driving cam through radius changes of the driving cam, and therefore the length of the driving rope is changed. The number of driving motors can be reduced, the control difficulty is simplified, and the rigidity of the continuum robot is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of continuum robots, and in particular relates to a driving device of a continuum robot. Background Art

[0002] Due to its flexibility, continuum robots have broad application prospects in the fields of medicine, industry and scientific research. However, there are also some defects, such as poor rigidity and only low load operation. In addition, the driving mechanism of the continuum robot is relatively complex. Basically, each or two driving ropes need to be connected to an actuator such as a motor, and a flexible continuum robot has at least ten or twenty driving ropes, which requires a large number of driving motors, resulting in the driving device being too large, which is not conducive to miniaturization, and a large number of driving motors will complicate its control program.

[0003] In addition, the rigidity of the continuum robot is relatively weak. Common methods to increase rigidity include blocking-type variable rigidity, adding airbags and obstructions to the continuum. By changing the air pressure, the friction is increased, thereby increasing the rigidity. This type of variable rigidity method makes the continuum robot structure bloated and requires a high-power air pump. In addition, adding special materials to the continuum can also increase the rigidity. The modified material has two states, solid and liquid, and the rigidity is increased by changing the state. This method is less efficient, and the solid-liquid state conversion of the material requires time and conditions. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0005] To this end, the present invention provides a driving device for a continuum robot, which can reduce the number of required driving motors to meet miniaturization requirements and simplify control difficulty, while also improving the stiffness of the continuum robot to ensure that the bending of the continuum robot is smoother and more stable.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: The present invention provides a driving device for a continuum robot, comprising a base, a rope-laying mechanism, a variable stiffness mechanism and a driving mechanism; The base has a connecting piece at one end for mounting the end of the continuum robot, the continuum robot has N curved segments and is driven by M driving ropes in total; The rope laying mechanism comprises a plurality of fixed pulleys and N+2 rope hole plates arranged at intervals; each fixed pulley is distributed in the area of ​​the base close to the connecting member, and is used to disperse and guide the driving rope; the spacing direction of two adjacent rope hole plates is consistent with the axial direction of the base, and each rope hole plate is provided with a rope threading hole corresponding to the position of each fixed pulley to constrain the corresponding driving rope; The variable stiffness mechanism is supported on the base and located between two adjacent rope hole plates, and areas for mounting the fixed pulley and the driving mechanism are formed on the outer sides of the two rope hole plates, respectively. The variable stiffness mechanism has M variable stiffness cams arranged on a common first rotating shaft, and each variable stiffness cam changes the tension of a corresponding driving rope after passing through the fixed pulley by changing its own radius; The driving mechanism comprises N cam mechanism assemblies, wherein a cam mechanism assembly is respectively arranged between two adjacent rope hole plates, and is used to drive a corresponding bending section of the continuum robot; a single cam mechanism assembly comprises M driving cams arranged on a common second rotating shaft, each driving cam is respectively provided with a follower on the upper part, and each follower is respectively provided with a rope threading hole for passing a corresponding driving rope at the top end; each driving cam adopts an elastic variable diameter cam, and the elasticity of the driving cam is utilized to ensure that it can rotate smoothly, and during the rotation of the driving cam, the bottom end of the follower rolls with the top end of the driving cam and drives the follower to move radially along the driving cam through the change of the radius of the driving cam itself, thereby changing the rope length of the driving rope so that the driven bending section produces a corresponding rotation angle.

[0007] In some embodiments, the first rotating shaft and each second rotating shaft in the cam mechanism assembly are located at the same height, and the axial direction is perpendicular to the direction of the driving rope in the base.

[0008] In some embodiments, the variable stiffness mechanism also includes a first motor fixed on the side wall of the base, which is used to drive the first rotating shaft. The M variable stiffness cams rotate synchronously with the first rotating shaft, and the radius of the variable stiffness cam gradually changes with the increase of the central angle of the variable stiffness cam.

[0009] In some embodiments, when the drive rope needs to be tightened, the variable stiffness cam is rotated in a direction in which its radius becomes larger by driving the first rotating shaft; when the drive rope needs to be loosened, the variable stiffness cam is rotated in a direction in which its radius becomes smaller by driving the first rotating shaft.

[0010] In some embodiments, the cam mechanism assembly further includes a second motor fixed to the side wall of the base, for driving the rotating shaft, and the M driving cams rotate synchronously with the second rotating shaft; the outer peripheral surface of the driving cam is divided into three curved surface segments, and the central angles corresponding to the three curved surface segments are respectively α 1 , α 2 , α 3 , and at the same time satisfy: α 1 ∈(90°, 180°), α2 ∈(90°, 180°), α 1 + α 2 + α 3 =360°, where the first curved surface segment and the second curved surface segment are working segments, and the central angle α 1 and α 2 They are the ranges of clockwise and counterclockwise rotation of the driving cam, respectively, which determine the rotation direction and range of a certain curved section of the driven continuum robot. The radius of the driving cam gradually changes with the increase of the respective central angles within each working section; the third curved surface segment is a transition segment that smoothly connects the first curved surface segment and the second curved surface segment.

[0011] In some embodiments, the driving cam is a solid structure made of elastic material; or, The driving cam is a hollow structure, which includes an outer ring and an inner ring arranged on a common second axis and a plurality of support members connected between the outer ring and the inner ring and evenly distributed around the circumference. The outer ring and the inner ring are both made of rigid materials, and the support members are elastic elements.

[0012] In some embodiments, the number of the support members is 6 to 8, and they are springs or S-shaped structures made of the same material as the outer ring and the inner ring.

[0013] In some embodiments, the outer contour of a certain working section in the driving cam is determined according to the following steps: Firstly, according to the structure and the rope threading method of the continuum robot, a series of driving rope length change values ​​corresponding to a series of bending angle values ​​of the controlled continuum are determined; then, according to the geometric position relationship between the second rotating shaft and the rope hole plates on both sides thereof, a series of radius values ​​of a certain working section in the driving cam are calculated from the series of driving rope length change values, and the series of radius values ​​are evenly distributed within the range of the central angle of a certain working section in the driving cam, so as to obtain the outer contour of a certain working section in the driving cam; Assume that due to the change in the radius of the driving cam Δ r The resulting change in the length of the drive rope is Δ l , Δ r With Δ l The following relationship is satisfied:

[0014] in, l 3 is the vertical distance between the follower on the driving cam and the rope hole plates on both sides thereof;l 4 It is the height difference between the follower and the corresponding rope threading hole on the rope hole plate when the driving cam is not rotating.

[0015] In some embodiments, the driving mechanism further comprises a limiting assembly fixedly connected to the base, for keeping the bottom end of the follower in contact with the top end of the driving cam, and constraining the follower to move only radially along the driving cam.

[0016] In some embodiments, the limit assembly includes N cross beams, and an end cover is respectively arranged at the top of each cross beam. Each cross beam is respectively located above a corresponding cam mechanism assembly and is fixedly connected to the base. The cross beam is provided with a plurality of limit through holes for the followers in the cam mechanism assembly to pass through, and a limit plate matching the cross-sectional size of the limit through hole is fixedly arranged on the follower for limiting the rotation of the follower in the limit through hole; the end cover is provided with a plurality of second through holes for the top of each follower to extend out, and a compression spring fixedly connected to the limit plate is respectively arranged in each second through hole.

[0017] The present invention provides a driving device for a continuum robot, which has the following characteristics and beneficial effects: 1. Arrange multiple cams with variable radius on a motor shaft to realize the function of a single motor controlling multiple drive ropes at the same time, reduce the number of drive motors in the drive device, reduce the complexity of the drive device, and simplify the control program.

[0018] 2. The variable stiffness cam can tighten the drive rope by utilizing its own radius change during rotation, and the stiffness of the continuum robot can be improved through the mutual antagonism of multiple drive ropes.

[0019] 3. Use an elastic variable diameter cam as the driving cam, and use its own elasticity to ensure that the driving cam can rotate smoothly, so as to ensure that the bending of the continuum robot is smoother and more stable; the outer contour of the driving cam is divided into two working sections and a transition section connecting the two. For each working section, the rotation direction and rotation range of a certain bending section of the driven continuum robot are accurately controlled by changing the radius of the driving cam itself, while the transition section can ensure the stability of the system when the control accuracy is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of a driving device of a continuum robot provided by an embodiment of the present invention; Figure 2 yes Figure 1 A schematic structural diagram of a first cam mechanism assembly in the driving device shown; Figure 3 yes Figure 2 A schematic structural diagram of a single driving cam in the first cam mechanism assembly shown; Figure 4 Yes Figure 3 A schematic diagram showing the design of the radius of the driving cam; Figure 5 is a schematic structural diagram of an improved driving cam provided in this embodiment; Figure 6 yes Figure 1 A schematic diagram of the structure of the limit assembly in the driving device shown; Figure 7 yes Figure 1 Schematic diagram of the layout of the drive rope in the drive device shown.

[0021] Description of labels: 100-driving device; 110-base, 111-first side wall, 112-second side wall, 113-connecting member; 120-rope laying mechanism, 121-fixed pulley, 122-stud, 123-first rope hole plate, 124-second rope hole plate, 125-third rope hole plate, 126-fourth rope hole plate; 130-variable stiffness mechanism, 131-first motor, 132-variable stiffness cam, 133-first bearing seat; 140-first cam mechanism assembly; 141-second motor, 142-driving cam, 142a-first curved surface segment, 142 b-second curved surface segment, 142c-third curved surface segment, 142d-first through hole, 142'-improved driving cam, A-outer ring, B-inner ring, C-supporting member, 143-second bearing seat, 144-follower, 144a-rope threading hole, 145-second rotating shaft, 146-coupling; 150-second cam mechanism assembly; 160-limiting assembly, 161-longitudinal beam, 162-cross beam, 162a-limiting through hole, 163-end cover, 163a-second through hole, 164-limiting plate, 165-compression spring; 170-driving rope; 200-continuum robot. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] On the contrary, the present application covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present application as defined by the claims. Further, in order to make the public have a better understanding of the present application, some specific details are described in detail in the detailed description of the present application below. Those skilled in the art can fully understand the present application without the description of these details.

[0024] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions that can be implemented in this application, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that can be produced by this application and the purposes that can be achieved, should still fall within the scope of the technical content disclosed in this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of narration, and are not used to limit the scope of the implementation of this application. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of this application without substantial change in the technical content.

[0025] See also Figure 1 , a driving device 100 of a continuum robot provided in an embodiment of the present invention comprises a base 110, a rope laying mechanism 120, a variable stiffness mechanism 130 and a driving mechanism; A base 110, one end of which is provided with a connector 113 for mounting the end of a continuum robot 200, the continuum robot 200 having N curved segments and driven by a total of M drive ropes 170; The rope laying mechanism 120 includes a plurality of fixed pulleys 121 and N+2 rope hole plates (123-126) arranged at intervals. Each fixed pulley 121 is distributed in the area near the connecting member 113 in the base 110. Through the guiding effect of the fixed pulley 121, the driving rope 170 is dispersed and ensured to be parallel. The spacing direction of two adjacent rope hole plates is consistent with the axial direction of the base 110. Each rope hole plate is provided with a rope threading hole corresponding to the position of each fixed pulley 121 to constrain the corresponding driving rope 170. The variable stiffness mechanism 130 is supported on the base 110 and is located between two adjacent rope hole plates, and the outer sides of the two rope hole plates are areas for installing the fixed pulley 121 and the driving mechanism respectively. The variable stiffness mechanism 130 has M variable stiffness cams 132 arranged on a common first rotating shaft, and the first rotating shaft is perpendicular to the direction of the driving rope 170. Each variable stiffness cam 132 changes the tension of a corresponding driving rope 170 after passing through the fixed pulley 121 by changing its own radius; A driving mechanism comprises N cam mechanism components (140, 150), wherein a cam mechanism component is respectively arranged between two adjacent rope hole plates, and is used to drive a corresponding curved section of a continuum robot 200; a single cam mechanism component comprises M driving cams arranged with a common rotation axis, each driving cam is respectively provided with a follower at the top, and each follower is respectively provided with a rope threading hole for passing a corresponding driving rope 170; each driving cam adopts an elastic variable diameter cam, and the elasticity of the driving cam is utilized to ensure that it can rotate smoothly, and during the rotation of the driving cam, the bottom end of the follower is in rolling contact with the top end of the driving cam and the follower is driven to move radially along the driving cam through the change of the radius of the driving cam itself, thereby changing the rope length of the driving rope 170 so that the driven curved section generates a corresponding rotation angle.

[0026] The specific implementation of the driving device 100 of this embodiment is described in detail below with reference to a specific application example and in conjunction with the accompanying drawings. The driving device 100 of this embodiment is used to drive a common continuum robot 200 on the market, which is composed of a number of threading discs and a middle elastic rod, has two bending degrees of freedom (i.e., N=2), and is driven by M=12 driving ropes 170 in total, and each bending section is controlled by 6 driving ropes.

[0027] See also Figure 1~Figure 5 , the driving device 100 of this embodiment includes: A base 110, one end of which is provided with a connector 113 for mounting the end of the continuum robot 200; The rope laying mechanism 120 comprises M fixed pulleys 121 and four rope hole plates (123-126) arranged at intervals; each fixed pulley 121 is distributed in the area near the connecting member 113 in the base 110 through a stud 122, and the driving rope 170 is dispersed and ensured to be parallel through the guiding effect of the fixed pulley 121; the spacing direction of two adjacent rope hole plates is consistent with the axial direction of the base 110, and each rope hole plate is provided with a rope threading hole corresponding to the position of each fixed pulley 121 to constrain the corresponding driving rope 170; The variable stiffness mechanism 130 is supported on the base 110 and is located between the first rope hole plate 123 and the second rope hole plate 124, and the outer sides of the two rope hole plates are areas for installing the fixed pulley 121 and the driving mechanism respectively. The variable stiffness mechanism 130 has M variable stiffness cams 132 arranged on a common first rotating shaft, and the first rotating shaft is perpendicular to the direction of the driving rope 170. Each variable stiffness cam 132 changes the tension of a corresponding driving rope 170 after passing through the fixed pulley 121 by changing its own radius; The driving mechanism includes a first cam mechanism assembly 140 and a second cam mechanism assembly 150. The first cam mechanism assembly 140 is located between the second rope hole plate 124 and the third rope hole plate 125, and the second cam mechanism assembly 150 is located between the third rope hole plate 125 and the fourth rope hole plate 126, and is used to drive a corresponding curved section of the continuum robot 200. A single cam mechanism assembly has M driving cams arranged with a common rotation axis, and each driving cam is respectively provided with a follower on the upper part, and each follower is respectively provided with a rope threading hole for passing a corresponding driving rope 170 at the top. Each driving cam adopts an elastic variable diameter cam, and the elasticity of the driving cam is used to ensure that it can rotate smoothly. During the rotation of the driving cam, the bottom end of the follower rolls with the top end of the driving cam and drives the follower to move radially along the driving cam through the change of the radius of the driving cam itself, thereby changing the rope length of the driving rope 170 so that the driven curved section produces a corresponding rotation angle.

[0028] Furthermore, the base 110 is mainly used to realize the installation and positioning of each component in this embodiment, and is connected to the end of the driven continuum robot 200. The length direction (defined as its axial direction) of the base 110 is parallel to the direction of the driving rope 170, and the base 110 is divided into several areas along its axial direction by the rope hole plates in the rope laying mechanism 120, wherein the fixed pulleys 121 of the rope laying mechanism 120 are arranged in the area close to the end of the continuum robot 200, and the variable stiffness mechanism 130, the first cam mechanism assembly 140 and the second cam mechanism assembly 150 are arranged in sequence in the area between the remaining two adjacent rope hole plates. The length directions (defined as their respective axial directions) of the variable stiffness mechanism 130, the first cam mechanism assembly 140 and the second cam mechanism assembly 150 are all perpendicular to the axial direction of the base 110, and their two ends are supported on the first side wall 111 and the second side wall 112 of the base 110 respectively.

[0029] Furthermore, in the rope laying mechanism 120, each fixed pulley 121 is fixed to the base 110 by a stud 122, so as to spread and lay the driving rope 170. Rope threading holes are respectively provided at set positions on the four rope hole plates (123, 124, 125, 126), and their positions correspond to the positions of the fixed pulleys 121, so as to constrain the driving rope 170 and prevent the driving rope 170 from being offset and misplaced. The ends of each driving rope 170 are finally fixed to the fourth rope hole plate 126. The four rope hole plates (123, 124, 125, 126) are all fixed to the base 110 by screws.

[0030] Furthermore, the variable stiffness mechanism 130 includes a first motor 131, a first rotating shaft, and M variable stiffness cams 132. The first motor 131 is fixed on the first side wall 111 of the base 110 between the first rope hole plate 123 and the second rope hole plate 124. The output end of the first motor 131 is connected to one end of the first rotating shaft, and the first rotating shaft is driven to rotate by the first motor 131. The M variable stiffness cams 132 are fixedly sleeved on the first rotating shaft and rotate synchronously with the first rotating shaft. The other end of the first rotating shaft is supported on the second side wall 112 of the base 110 between the first rope hole plate 123 and the second rope hole plate 124 through the first bearing seat 133. Each variable stiffness cam 132 adopts a variable diameter cam, and specifically, the radius of the variable stiffness cam 132 gradually increases or decreases as the central angle of the variable stiffness cam 132 increases. When the driving rope 170 needs to be tensioned, the first motor 131 drives the first rotating shaft to rotate the variable stiffness cam 132 in the direction of increasing its radius. When the driving rope 170 needs to be loosened, the first motor 131 drives the first rotating shaft to rotate the variable stiffness cam 132 in the direction of decreasing its radius. When the driving rope 170 is tensioned, the restraining force generated between the driving ropes 170 is similar to the mutual antagonism between antagonistic muscles, thereby improving the stiffness of the continuum robot 200. The mutual antagonism described in this article can refer to muscle antagonism, which is a part of human muscle. It is a muscle located on the opposite side of the prime mover and relaxes and stretches at the same time during the process of the prime mover contracting to complete the action. For example, in the elbow flexion action, the prime movers are the biceps brachii and the brachialis, and the triceps brachii located on the opposite side of them relaxes and stretches at the same time, which is the antagonist muscle in the elbow flexion action, and vice versa. The antagonist and the prime mover are opposite in form, but their functions of surrounding joint movement are unified and coordinated.

[0031] Furthermore, the structures of the cam mechanism components in the driving mechanism are the same, and the first cam mechanism component 140 is now taken as an example for description. Referring to 2, the first cam mechanism assembly 140 includes a second motor 141, a second rotating shaft 145, M driving cams 142 and M followers 144. The second motor 141 is fixed on the first side wall 111 of the base 110 between the second rope hole plate 124 and the third rope hole plate 125. The output end of the second motor 141 is connected to one end of the second rotating shaft 145, and the second rotating shaft 145 is driven by the second motor 141 to rotate. The M driving cams 142 are fixedly sleeved on the second rotating shaft 145 and rotate synchronously with the second rotating shaft 145. The other end of the second rotating shaft 145 is supported on the second side wall 112 of the base 110 between the second rope hole plate 124 and the third rope hole plate 125 through a second bearing seat 143. During the rotation of the driving cam 142, the bottom end of the follower 144 maintains rolling contact with the top end of the driving cam 142, and a rope threading hole 144a for passing a corresponding driving rope 170 is provided at the top end of the follower 144. Optionally, a coupling 146 is further provided between the output end of the second motor 141 and the second rotating shaft 145 to ensure smooth transmission of power.

[0032] Further, see Figure 3 , is a structural schematic diagram of a driving cam 142 in the first cam mechanism assembly 140, and other driving cams are similar thereto. The driving cam 142 is provided with a first through hole 142d in the middle for assembly with the second rotating shaft 145, and the rest of the driving cam 142 is a solid structure. In this embodiment, the second rotating shaft 145 and the first through hole 142d of the driving cam 142 both have a square cross section. Considering that in the process of driving the continuum robot 200, there is a situation where the tension of some driving ropes 170 is too large. If a rigid driving cam is used, there is a situation where the driving rope 170 is broken or the continuum robot 200 is stuck and cannot move. In addition, considering that the driving device may have errors in the processing and assembly process, which may also cause the tension of the driving rope 170 to be too large, each driving cam 142 is made of elastic material, and the elasticity of the driving cam itself is used to ensure that the driving cam can rotate smoothly, thereby ensuring that the bending of the continuum robot 200 is smoother and more stable. The driving cam 142 adopts a variable diameter cam, and the outer peripheral surface of the driving cam 142 is divided into three curved surface segments, which are respectively recorded as the first curved surface segment 142a, the second curved surface segment 142b and the third curved surface segment 142c. The central angles corresponding to the three curved surface segments are α 1 , α 2 , α 3 , and at the same time satisfy: α 1 ∈(90°, 180°), α2 ∈(90°, 180°), α 1 + α 2 + α 3 =360°, wherein the first curved surface segment 142a and the second curved surface segment 142b are working segments, and the central angle α 1 and α 2 They are the ranges of the clockwise and counterclockwise rotation of the driving cam 142, respectively, which determine the rotation direction and range of a certain curved section of the driven continuum robot 200. The radius of the driving cam 142 is set to gradually change with the increase of the respective center angles within each working section; the third curved section 142c is a transition section connecting the first curved section 142a and the second curved section 142b, so that the center angle of the outer contour of the driving cam 142 is 360°. The driving rope 170 generally does not pass through the third curved section 142c. When the control accuracy of the device is reduced, the driving rope 170 may pass through a small part of the third curved section 142c, which plays a role in stabilizing the system. It can be understood that setting the center angle in this way can make full use of the entire outer circumference of the driving cam 142. If the center angle α 1 , α 2 are less than or equal to 90 degrees, then will be greater than or equal to 180 degrees, so that the outer peripheral surface of the driving cam 142 is not fully utilized; if the central angle α 1 , α 2 If the angles of the first curved surface segment 142a and the second curved surface segment 142b are both equal to 180 degrees, there will be a lack of a transition section, and the first curved surface segment 142a and the second curved surface segment 142b will be directly connected. A sudden change in the radius of the driving cam may occur at the connection point, which is not conducive to system stability.

[0033] The design process of each curved surface segment of the driving cam 142 is briefly described below: The design of the curved surface segment of the driving cam 142 is related to the corresponding driving rope 170. First, according to the structure of the continuum robot 200 and the rope threading method, the relationship between the bending angle of the controlled continuum and the length change of the driving rope 170 is calculated; then, according to the geometric position relationship between the second rotating shaft 145 and the rope hole plates on both sides of the second rotating shaft 145, the relationship between the bending angle of the controlled continuum and the radius of the driving cam 142 is further calculated. Then, for the angle series values ​​of the controlled continuum bending in one direction, the series values ​​corresponding to the radius of the driving cam 142 are calculated, and these values ​​are evenly distributed to the center angle of the first curved surface segment 142a in the driving cam 142. α 1(e.g., 150 degrees), thereby obtaining the first curved surface segment 142a of the driving cam 142. Similarly, for the reverse bending condition of the continuum robot 200, the second curved surface segment 142b of the driving cam can be obtained according to the same steps as above. The third curved surface segment 142c is a transition profile, which does not require calculation, but only requires smooth transition, connecting the first curved surface segment 142a and the second curved surface segment 142b of the driving cam 142.

[0034] Further, see Figure 4 , when the driving cam 142 is not rotating and is in the initial position, the follower 144 and the driving rope 170 are located in the solid line position; when the driving cam 142 rotates in the direction in which its radius increases, the follower 144 and the driving rope 170 are located in the dotted line position. Since the present invention does not involve the design of the configuration of the continuum robot 200 itself, it uses a continuum robot with a common configuration. Therefore, the relationship between the bending angle of the controlled continuum and the change in the length of the driving rope 170 is taken as a known condition and is not calculated and described separately. Assume that the displacement of the follower 144 along the radial direction of the driving cam 142 is h , the radius change value of the driving cam 142 is Δ r , and satisfies Δ r = h , assuming that the change in length of the drive rope 170 due to the change in the radius of the drive cam 142 is Δ l The initial length and the changed length of the driving rope 170 between the second rope hole plate 124 and the third rope hole plate 125 are respectively l 1 , l 2 ,pass Figure 4 The geometric relationships shown list equations:

[0035] Combining the above three equations, we get:

[0036] in, l 3 The vertical distance between the follower 144 and the second rope hole plate 124 and the third rope hole plate 125 on both sides thereof are taken to be equal; l 4 When the driving cam is not rotating, the height difference between the rope hole 144a on the follower 144 and the rope hole on the second rope hole plate 124 is l 3 and l 4 All are known values.

[0037] Based on the above formula, the radius change value Δ of the driving cam 142 is obtained: rand the driving rope 170 rope length change Δ l The relationship between the radius change Δ of the driving cam 142 can be obtained. r and the relationship between the bending angle of the controlled continuum.

[0038] Furthermore, the embodiment of the present invention also provides an improved driving cam 142', which is different from the driving cam 142 in that the improved driving cam 142' is partially hollowed out in the shape of the driving cam 142, and a support member C is provided in the hollowed out portion to form a structure similar to a wheel hub. Figure 5 , the improved driving cam 142' comprises an outer ring A and an inner ring B arranged on a common second axis 145, and a plurality of support members C connected between the outer ring A and the inner ring B and evenly distributed around the circumference, and the number of support members C is preferably 6 to 8. The outer ring A and the inner ring B are both made of rigid materials, and the support member C is an S-shaped structure made of rigid materials and integrally formed with the inner and outer rings, and both ends of the S-shaped structure are straight and point to the axis of the driving cam; or, the support member C is an elastic element, such as a spring. In this embodiment, the support member C is an S-shaped structure integrally formed with the inner and outer rings, the thickness a of the support member C is 0.5mm, the distance from the outer circumference of the inner ring B to the outer circumference of the outer ring A is b=9mm, and the distance from the outer circumference of the inner ring B to the inner circumference of the outer ring A is c=6mm, and the improved driving cam 142' is obtained by 3D printing with resin materials. The outer circumference of the outer ring A and the inner ring B is an equidistant curve, which is the same as the design process of the outer circumference of the driving cam 142, and is also divided into three curved surface segments, which will not be repeated here. After the support member C is added, when the inner ring B is restricted from displacement and the force on the outer ring A exceeds a certain threshold, the support member C will be compressed and produce elastic deformation, so that the outer ring A moves along the force direction to ensure that the bending of the continuum robot 200 is smoother and more stable. Compared with the driving cam 142, the improved driving cam 142' has a lighter dead weight. In addition, because the outer ring A of the improved driving cam 142' is made of rigid material, it has better control accuracy than the driving cam 142.

[0039] Furthermore, in order to ensure that the driving cam 142 and its corresponding follower 144 can maintain a rolling contact state during the operation of the driving device 100, the driving mechanism of this embodiment further includes a limit assembly 160, see Figure 1 , Figure 2 , Figure 6The limiting assembly 160 includes a frame body formed by two longitudinal beams 161 and a plurality of transverse beams 162 fixedly connected, and an end cover 163 is respectively arranged at the top of each transverse beam 162. The axial direction of the two longitudinal beams 161 is consistent with the axial direction of the base 110, and they are respectively fixed to the top of the first side wall 111 and the second side wall 112 of the base 110 by bolts. The number of transverse beams 162 and end covers 163 is the same as the number of cam mechanism assemblies in the driving mechanism. In this embodiment, two transverse beams 162 and two end covers 163 are provided, and each transverse beam 162 is respectively fixed to the top of a corresponding cam mechanism assembly through the longitudinal beam 161. A limiting through hole 162a corresponding to each follower 144 in the cam mechanism assembly is opened on the transverse beam 162, and each follower 144 passes through a corresponding limiting through hole 162a and is fixed on the follower 144. A limiting piece 164 matching the cross-sectional size of the limiting through hole 162a is fixedly provided, and is used to limit the rotation of the follower 144 in the limiting through hole 162a. In this embodiment, the limiting piece 164 and the limiting through hole 162a both have a square cross-section, and the limiting piece 164 can move along the axial direction (i.e., the up and down direction) of the limiting through hole 162a with the follower 144 in the limiting through hole 162a without being able to rotate; the axial direction of each end cover 163 is consistent with the cross beam 162, and the end cover 163 is provided with a plurality of second through holes 163a, each for the top of a corresponding follower 144 to extend out, and a compression spring 165 fixedly connected to the limiting piece 164 on the corresponding follower 144 is respectively provided in each second through hole 163a, and is used to ensure that the bottom end of the follower 144 is in full contact with the top of the driving cam 142.

[0040] Further, see Figure 7 , is a threading diagram of the drive device 100 of this embodiment. In this example, the continuum robot 200 is divided into two sections with two degrees of freedom. The first section bends up and down, and the second section bends left and right. Each section is driven by six ropes, and there are 12 driving ropes 170 in total. In this driving device 100, a variable stiffness mechanism 130 is provided, and a first cam mechanism assembly 140 and a second cam mechanism assembly 150 are provided to control the movement of the two sections of the continuum respectively. Therefore, if the continuum robot 200 is divided into N sections, then a total of N+1 cam shafts need to be provided, and the number of cams on each shaft should correspond to the number of driving ropes 170. If the present invention is used to drive other continuum robots, the number of cam shafts and the number of cams on the cam shafts need to be increased or decreased according to the number of sections (number of degrees of freedom) of the continuum robot and the number of driving ropes.

[0041] Take the drive rope 170 in this embodiment as an example, see Figure 7After the driving rope 170 starts from the continuum robot 200, it first passes through the connecting member 113, then passes through the guide dispersion of the fixed pulley 121, passes through the first rope hole plate 123, bypasses the lower contour of the variable stiffness cam 132, and then passes through the second rope hole plate 124, the rope threading hole 144a of the follower 144 on the driving cam in the first cam mechanism assembly 140, the third rope hole plate 125, and the rope threading hole of the follower on the driving cam in the second cam mechanism assembly 150, and finally is fixed on the fourth rope hole plate 126. When each motor drives the corresponding rotating shaft to drive the driving cam to rotate, the follower moves up and down, causing the rope length of the driving rope 170 to change, thereby causing the continuum robot 200 to bend. It should be noted that each rotating shaft is arranged in parallel and at the same height, and the rotating shaft is perpendicular to the direction of the driving rope in this driving device.

[0042] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0043] Although examples of the present invention have been shown and described above, it is to be understood that the above examples are illustrative and are not to be construed as limitations of the present invention, and that a person skilled in the art may make changes, modifications, substitutions and variations to the above examples within the scope of the present invention.

Claims

1. A driving device for a continuum robot, characterized in that: It includes a base, a rope-laying mechanism, a variable stiffness mechanism and a driving mechanism; The base has a connecting piece at one end for mounting the end of the continuum robot, the continuum robot has N curved segments and is driven by M driving ropes in total; The rope laying mechanism comprises a plurality of fixed pulleys and N+2 rope hole plates arranged at intervals; each fixed pulley is distributed in the area of ​​the base close to the connecting member, and is used to disperse and guide the driving rope; the spacing direction of two adjacent rope hole plates is consistent with the axial direction of the base, and each rope hole plate is provided with a rope threading hole corresponding to the position of each fixed pulley to constrain the corresponding driving rope; The variable stiffness mechanism is supported on the base and located between two adjacent rope hole plates, and areas for mounting the fixed pulley and the driving mechanism are formed on the outer sides of the two rope hole plates, respectively. The variable stiffness mechanism has M variable stiffness cams arranged on a common first rotating shaft, and each variable stiffness cam changes the tension of a corresponding driving rope after passing through the fixed pulley by changing its own radius; The driving mechanism comprises N cam mechanism assemblies, wherein a cam mechanism assembly is respectively arranged between two adjacent rope hole plates, and is used to drive a corresponding bending section of the continuum robot; a single cam mechanism assembly comprises M driving cams arranged on a common second rotating shaft, each driving cam is respectively provided with a follower on the upper part, and each follower is respectively provided with a rope threading hole for passing a corresponding driving rope at the top end; each driving cam adopts an elastic variable diameter cam, and the elasticity of the driving cam is utilized to ensure that it can rotate smoothly, and during the rotation of the driving cam, the bottom end of the follower rolls with the top end of the driving cam and drives the follower to move radially along the driving cam through the change of the radius of the driving cam itself, thereby changing the rope length of the driving rope so that the driven bending section produces a corresponding rotation angle.

2. The driving device according to claim 1, characterized in that: The first rotating shaft and each second rotating shaft in the cam mechanism assembly are located at the same height, and the axial direction is perpendicular to the direction of the driving rope in the base.

3. The driving device according to claim 1, characterized in that: The variable stiffness mechanism also includes a first motor fixed on the side wall of the base, which is used to drive the first rotating shaft. The M variable stiffness cams rotate synchronously with the first rotating shaft, and the radius of the variable stiffness cam gradually changes with the increase of the central angle of the variable stiffness cam.

4. The driving device according to claim 1, characterized in that: When the drive rope needs to be tightened, the first rotating shaft is driven to rotate the variable stiffness cam in a direction in which its radius becomes larger. When the drive rope needs to be loosened, the first rotating shaft is driven to rotate the variable stiffness cam in a direction in which its radius becomes smaller.

5. The driving device according to claim 1, characterized in that: The cam mechanism assembly further includes a second motor fixed to the side wall of the base, which is used to drive the rotating shaft. The M driving cams rotate synchronously with the second rotating shaft. The outer peripheral surface of the driving cam is divided into three curved surface segments. The central angles corresponding to the three curved surface segments are α 1. α 2. α 3, and at the same time: α 1∈(90°, 180°), α 2∈(90°, 180°), α 1+ α 2+ α 3 = 360°, where the first curved segment and the second curved segment are working segments, and the central angle α 1 and α 2 are the ranges of the driving cam for clockwise and counterclockwise rotation, respectively, which determine the rotation direction and range of a certain curved segment of the driven continuum robot. The radius of the driving cam gradually changes with the increase of the respective central angles within the range of each working segment; the third curved segment is a transition segment that smoothly connects the first curved segment and the second curved segment.

6. The driving device according to claim 5, characterized in that: The driving cam is a solid structure made of elastic material; or, The driving cam is a hollow structure, which includes an outer ring and an inner ring arranged on a common second axis and a plurality of support members connected between the outer ring and the inner ring and evenly distributed around the circumference. The outer ring and the inner ring are both made of rigid materials, and the support members are elastic elements.

7. The driving device according to claim 6, characterized in that: The number of the support members is 6 to 8, and they are springs or S-shaped structures made of the same material as the outer ring and the inner ring.

8. The driving device according to any one of claims 5 to 7, characterized in that: Follow the steps below to determine the outer contour of a certain working section in the driving cam: Firstly, according to the structure and the rope threading method of the continuum robot, a series of driving rope length change values ​​corresponding to a series of bending angle values ​​of the controlled continuum are determined; then, according to the geometric position relationship between the second rotating shaft and the rope hole plates on both sides thereof, a series of radius values ​​of a certain working section in the driving cam are calculated from the series of driving rope length change values, and the series of radius values ​​are evenly distributed within the range of the central angle of a certain working section in the driving cam, so as to obtain the outer contour of a certain working section in the driving cam; Assume that due to the change in the radius of the driving cam Δ r The resulting change in the length of the drive rope is Δ l , Δ r With Δ l The following relationship is satisfied: in, l 3 is the vertical distance between the follower on the driving cam and the rope hole plates on both sides thereof; l 4 is the height difference between the follower and the corresponding rope threading hole on the rope hole plate when the driving cam is not rotating.

9. The driving device according to claim 1, characterized in that: The driving mechanism also includes a limiting assembly fixedly connected to the base, which is used to keep the bottom end of the follower in contact with the top end of the driving cam and restrict the follower to move only along the radial direction of the driving cam.

10. The driving device according to claim 9, characterized in that: The limit assembly includes N cross beams, and an end cover is respectively arranged at the top of each cross beam. Each cross beam is respectively located above a corresponding cam mechanism assembly and is fixedly connected to the base. The cross beam is provided with a plurality of limit through holes for the followers in the cam mechanism assembly to pass through, and a limit plate matching the cross-sectional size of the limit through hole is fixedly arranged on the follower for limiting the rotation of the follower in the limit through hole; the end cover is provided with a plurality of second through holes for the top of each follower to extend out, and a compression spring fixedly connected to the limit plate is respectively arranged in each second through hole.

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